(+)-decumbensine and (+)-epi-α-decumbensine are not α-hydroxybenzyltetrahydroisoquinolines

Rozwadowska, Maria D.; Matecka, Dorota; Brózda, Danuta

doi:10.1016/s0040-4039(01)93346-5

Cited by 8 publications

(11 citation statements)

References 7 publications

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“…5 In 1989, Rozwadowska synthesized compounds 5 and 6 and found that spectra of the synthetic material did not match the published spectra of decumbensine and epi-a-decumbensine. 6 In this paper, we present evidence that decumbensine and egenine are identical and that epi-a-decumbensine and corytensine are identical.7…”

mentioning

confidence: 77%

“…[R-(JZ*,S*)]-a-l, 6,7,isoquinoline-5methanol (13). To a suspension of the tartrate of 12 (1.33 g, 2.79 mmol) in CH2C12 (50 mL) was added an equal volume of saturated Na2C03.…”

Section: Methodsmentioning

confidence: 99%

“…[JZ-(fl*,/Z*)]-a-l, 6,7,isoquinoline-5-methanol (15). A solution of the pivaloate 14 (501 mg, 1.22 mmol) in THF (10 mL) was added dropwise to a suspension of LAH (139 mg) in THF at 0 °C.…”

Section: Methodsmentioning

confidence: 99%

“…Caled for C19H15N06: C, 64.59; H, 4.28. Found: C, 64.41; , 4.31. (lS)-trans-l, 5,6,isoquinolin-3-one (16t) was obtained in 86% yield (464 mg) as a white solid from 500 mg of 15:…”

Section: Methodsmentioning

confidence: 99%

“…It was at about this time that Rozwadowska reported the synthesis of 6 and 5 in racemic form and noted the mismatch. 6 The Polish workers went on to suggest that epi-a-decumbensine and corytensine might be one and the same. Unfortunately, samples of the natural products were not availa- Elaboration by Directed Metalation and Stereochemical Correlation.…”

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confidence: 99%

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Synthesis of the phthalide isoquinoline alkaloids (-)-egenine, (-)-corytensine, and (-)-bicuculline by asymmetric carbonyl addition of chiral dipole-stabilized organometallics

Rein¹,

Gawley²

1991

J. Org. Chem.

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mentioning

confidence: 77%

“…[R-(JZ*,S*)]-a-l, 6,7,isoquinoline-5methanol (13). To a suspension of the tartrate of 12 (1.33 g, 2.79 mmol) in CH2C12 (50 mL) was added an equal volume of saturated Na2C03.…”

Section: Methodsmentioning

confidence: 99%

“…[JZ-(fl*,/Z*)]-a-l, 6,7,isoquinoline-5-methanol (15). A solution of the pivaloate 14 (501 mg, 1.22 mmol) in THF (10 mL) was added dropwise to a suspension of LAH (139 mg) in THF at 0 °C.…”

Section: Methodsmentioning

confidence: 99%

“…Caled for C19H15N06: C, 64.59; H, 4.28. Found: C, 64.41; , 4.31. (lS)-trans-l, 5,6,isoquinolin-3-one (16t) was obtained in 86% yield (464 mg) as a white solid from 500 mg of 15:…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Synthesis of the phthalide isoquinoline alkaloids (-)-egenine, (-)-corytensine, and (-)-bicuculline by asymmetric carbonyl addition of chiral dipole-stabilized organometallics

Rein¹,

Gawley²

1991

J. Org. Chem.

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Synthesis of isoquinoline alkaloids. Total synthesis of (±)‐tetrahydroescholamine and its (±)‐threo‐ and (±)‐erythro‐α‐hydroxy analogs

1991

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The studied tetrahydroisoquinolines 1, 2 and 3 were synthesized from a common intermediate 6, which was prepared b y addition of the lithium salt of dithiane 5 to hydrastinine chloride (4).In a previous'' paper we have described a total synthesis of secoberbine alkaloids in which 1,3-dithianes and 3,4-dihydroisoquinolinium salts are used as building blocks in the construction of the alkaloid carbon skeleton. The 1,3-dithiane masking group can then be removed either reductively with Raney nickel or by hydrolysis to afford 1 -benzyl-or 1 -benzoyltetrahydroisoquinolines, respectively. The success of this strategy has encouraged us to perform a synthesis of three other isoquinoline alkaloids, namely ( f )-tetrahydroescholamine (1) and ( f )-threo-and (+)-erythro-(a-hydroxybenzy1)tetrahydroisoquinolines 2 and 3, utilizing also a common intermediate. The latter two structures, 2 and 3, were postulated by R.-S. Xu et al.*' as (+)-decumbensine and (+)-epi-a-decumbensine, two alkaloids isolated recently from Corydalis decumbens. As we have briefly reported3', our synthetic amino alcohols 2 and 3 are not identical with the two alkaloids, but differ significantly from the latter in their spectroscopic data. This difference was unambiguously established by a comparison (TLC, Analtech silica gel GHLF, benzene/methanol, 9: 1) with an authentic sample of (+)-decumbensine. Additional structural proof for 2 and 3 is provided by converting the alcohols 2 and 3 into ( +)-tetrahydroescholamine (I), which is also prepared in the course of this study by a total synthesis.The key intermediate in this study, the addition product 6, is obtained in 89% yield by the action of lithiated 1,3-dithiane 5 on the iminium salt 4in T H F at -76°C. Its 'H-NMR spectrum reveals a NCH3 singlet at 6 = 2.58, a 1-H singlet at 6 = 3.95, one AB quadruplet centered at 6 = 5.89 ( J = 1.5 Hz) and one singlet at 6 = 5.96, both characteristic of methylenedioxy protons. Two singlets at 6 = 6.36 and 6.45 and a multiplet between 6 = 6.75-7.29 represent the five aromatic protons. The molecular ion is not detected by EI-MS; instead, we have found two fragment ions at m/z = 190 and 240 corresponding to two parts of the molecule formed by cleavage of the central bond between the two benzylic moieties.Reductive desulfurization of adduct 6 with Raney nickel in T H F at room temperature results in (&)-tetrahydroescholamine (1) in 83% yield. The general spectroscopic data of this benzyltetrahydroisoquinoline correspond to those of ( +)-tetrahydroescholamine prepared from the methoiodide of natural escholamine by reduction with zinc in hydrochloric acid4), or by the Bischler-Napieralski synthesis5). Its 'H-NMR spectrum exhibits a NCH3 singlet at 6 = 2.45, the I-H proton signal at 6 = 3.63 ist split in to a triplet ( J = 6 Hz). However, the neighboring benzylic proton signals are hidden by other methylene proton signals in a multiplet between 6 = 2.67-2.96. The protons of one of the methylenedioxy substitutents form an AB quadruplet centered at 6 = 5.86 ( J = 1.5 Hz), while...

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Synthetic and stereochemical studies on phthalideisoquinoline hemiacetals

Rozwadowska¹,

Matecka²

1991

Liebigs Ann. Chem.

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The two new phthalideisoquinoline hemiacetals rac‐egenine (3) and rac‐corytensine (4) are prepared by stereoselective DIBAL reduction of rac‐bicuculline (1) and rac‐adlumidine (2), respectively. The identity of egenine (3) with decumbensine as well as of corytensine (4) with epi‐α‐decumbensine and humosine A is postulated. The configuration around the anomeric center in natural (+)‐egenine (3), (+)‐corytensine (4) and (−)‐narcotine hemiacetal (7) is deduced as (7′S), (7′R) and (7′R), respectively.

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(+)-decumbensine and (+)-epi-α-decumbensine are not α-hydroxybenzyltetrahydroisoquinolines

Cited by 8 publications

References 7 publications

Synthesis of the phthalide isoquinoline alkaloids (-)-egenine, (-)-corytensine, and (-)-bicuculline by asymmetric carbonyl addition of chiral dipole-stabilized organometallics

Synthesis of the phthalide isoquinoline alkaloids (-)-egenine, (-)-corytensine, and (-)-bicuculline by asymmetric carbonyl addition of chiral dipole-stabilized organometallics

Synthesis of isoquinoline alkaloids. Total synthesis of (±)‐tetrahydroescholamine and its (±)‐threo‐ and (±)‐erythro‐α‐hydroxy analogs

Synthetic and stereochemical studies on phthalideisoquinoline hemiacetals

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